I was asked this question recently and thought it might help a few folk…..
J H. has a problem with a Scot,s Pine and we wondered if you could help ?
When purchased the tree had a shari created the entire length of the trunk approx 24 inches. Had the tree one year and the resin still emits from the surrounding trunk. How can this be stopped ? The resin has also flowed onto the old bark. How can the resin be removed without damaging the bark ? “
This is not an uncommon problem with some trees.
In my experience there are four species that should never have shari cut into them. Larch, Cedar, Pines and Hemlock (Tsuga). All of these can bleed sap profusely and on occasions for a very long time as you describe. I am not a fan of shari in general. If the tree is yamadori and it came with, then that’s perfect but when used as a styling element I feel it rarely brings much value to the table. The exception to this would be juniper and possibly taxus but then these species have bark with a very linear sap flow and tend to create their own areas of bare wood with little help.
The reason I suggest the above species are not suitable for shari is the fact that they have very thick bark, resinous sap and also produce huge amounts of callous tissue. I have seen larch close up a 15-20mm wide shari in a single season. The fresh young and smooth callous is usually very thick, and invariably a different colour to the old bark and can look like the tree had an unpleasant meeting with a mastic gun. Sure you can re-cut each year but after a few years things are going to get exceptionally ugly. Another reason why you should not use shari on these trees is that they do bleed sticky resinous sap which invariably goes white and as you say can get onto old craggy bark and ruin it. Besides that, if the tree already has old craggy bark how could an artificial shari possibly improve it?
First off it will be necessary to remove all the old dried resin. You can do this by heating gently and wire brushing it away but you will ruin a lot of brushes and end up with it covering everything. Better to dissolve it slowly using turpentine. NOT white spirit which is a petroleum derived compound. Turpentine (also called spirit of turpentine, oil of turpentine, wood turpentine and colloquially turps) is a fluid obtained by the distillation of resin obtained from live trees, mainly pines. This will dissolve the resin and it can be cleaned away easily. A little patience and care will get the tree cleaned up nicely and the shari back to bare wood. Once clean take a little gas torch and burn the area that has been bleeding. Blacken the surface all over and the surrounding area. This will cauterize the open sap vessels and stem the flow. High heat is required but not for a long time. Wood and bark are poor conductors of heat so the quick application required to seal off the vessels will not cause a wider problem. Do bear in mind that resin is flammable and the heat will boil it at the surface. I worked on a Japanese black pine a few years ago and it had a large pruned branch stub that I turned into a jin. Upon burning it to finish the surface the sap inside got hot and it sat there burning like a candle for ages. I think it would have burned all day 🙂